Steve Kemp, of the Debian Administration blog, recently published an in-depth tutorial of how to create a dashboard using Node.js and Redis. Here's a little of what he had to say, followed by a link to the original post.
The basic goal of a dashboard is to show you interesting activity in real-time. That interesting activity might be simple text strings describing events, load graphs, or even sales-counts. If you're running a cluster of some sort a dashboard is very useful, because it allows you to see events that have happened globally - rather than logging on to each machine in turn to pull out metrics and ensure all is well.
Once you realize that you want to combine events from multiple machines it becomes obvious that you need to listen on the network, somehow, to accept the submission of "interesting events". In the past I've used various things to run simple servers, from Apache + CGI scripts, to sinatra, and most recently node.js.